Dental implant with porous body

ABSTRACT

A dental implant having two distinct regions, a coronal region and a bone fixation region. The coronal region has a smooth transgingival section and an interface for connecting to a dental component. The bone fixation region has an elongated cylindrical shape and is formed as a porous structure that extends completely through the bone fixation region.

This application is a continuing application of Ser. No. 10/375,343filed on Feb. 27, 2003 now U.S. Pat. No. 7,291,012 and entitled “DentalImplant with Porous Body.”

FIELD OF THE INVENTION

The disclosure herein generally relates to dental implants forosseointegration in alveolar bone and, more particularly, to dentalimplants having a porous body.

BACKGROUND OF THE INVENTION

Much effort has been directed to integrating dental implants intosurrounding bone. Ideally, a dental implant would be placed intoalveolar bone, and thereafter bone would readily grow into the surfaceof the implant. To achieve this objective, many different surfacetechnologies have been applied to dental implants. In some instances,the surface of the implant is roughened, grit-blasted, plasma-sprayed,or microtextured. In other instances, the surface is coated with abiological agent, such as hydroxylapatite (known as HA). In all of theseinstances, the goal is the same: Produce a surface on the dental implantinto which surrounding bone will grow or bond.

Porous coatings have also been applied to surfaces of dental implants.U.S. Pat. No. 5,989,027 entitled: “Dental Implant Having MultipleTextured Surfaces” to Wagner et al. (and expressly incorporated hereinby reference) teaches a dental implant having multiple textured surfaceson the same implant. One surface includes a porous coated substrate, andanother surface includes a nonporous surface adapted to encourage bonegrowth or bonding.

Porous coatings are advantageous since bone will indeed grow into thesurface of the implant. Osseointegration, to a limited extent then, hasbeen achieved with porous coated surfaces. These surfaces though are farfrom ideal in terms of accepting and encouraging bone growth into thebody of the implant.

As one disadvantage, porous surfaces are often thin coatings applied tothe metallic substrate of the implant. Bone surrounding the implant canonly grow into the coating itself. Bone cannot grow through the coatingand into the metallic substrate. The depth of bone growth into theimplant is limited to the depth of the porous coating. Bone simplycannot grow completely through the implant.

As another disadvantage, porous surfaces on dental implants do not havethe proper geometric size and structure to maximize bone growth into theimplant. A porous structure that more closely emulated the size andstructure of bone itself would more fully accept and encourage bonegrowth and bonding into the structure.

It therefore would be desirable to have a dental implant that offersoptimum anchoring in bone with bone growth into a completely porousbody. The present invention realizes this advantage and others asprovided herein.

SUMMARY OF THE INVENTION

The present invention is directed toward a dental implant forintegrating with surrounding bone. The implant includes two separate anddistinct bodies, a coronal body and a bone fixation body. Together,these bodies form a complete dental implant.

The coronal body is located at the coronal end of the implant andincludes a dental interface adapted to connect with another dentalcomponent, such as an abutment. In the preferred embodiment, thisinterface includes a hexagonal connector, such as a hexagonal protrusionor recess. A threaded bore may be provided to receive a dental screw.The screw assists in connecting the dental component to the dentalimplant.

Preferably, the coronal body is formed of a solid metal piece, such astitanium or titanium alloy. The body is formed from a machining processand has a generally short, cylindrical shape with a top surface havingthe dental interface. A smooth, outer transgingival section is providedalong the side of the body. This transgingival section protrudes throughthe gum tissue or gingival tissue in the jawbone of the patient.

The bone fixation body is formed of a porous metal, such as titanium.Preferably, the body is formed with a sintering process, is completelyporous, and does not include a metal substrate. In cross section then,the body has a porous structure with no solid metal substrate.

The coronal body (formed of solid metal) and the bone fixation body(formed of a completely porous structure) are permanently connectedtogether. When connected, the two bodies form a dental implant.Preferably, these two bodies are connected with a sintering process.

One important advantage of the present invention is that the body of theimplant is completely porous. This porous structure extends entirelythrough the body of the implant along the region where the implantengages bone. As such, the depth of bone growth into the implant is notrestricted to a thin porous coating. Instead, bone can grow completelyinto and even through the body of the implant. The implant, then, canbecome fully integrated into surrounding bone with the structure of bonedispersed throughout the body of the implant.

As another advantage, the geometric structure of the porous body isshaped and sized to emulate the shape and size of natural bonesurrounding the implant. Specifically, the porous structure of the bonefixation body thus replicates the porous structure of natural boneitself. The porous structure, thus, readily accepts and encouragessurrounding bone to grow into and even through the body of the implant.

As another advantage, the bone fixation body may be doped with bonegrowth agents to enhance and stimulate bone growth. These agents can beplaced throughout the bone fixation body so bone grows completelythrough the implant. Bone growth, as such, is not restricted to thesurface of the implant.

As noted, the porous structure of the implant enables bone to grow intoand completely through the implant itself. Growth deep into the body ofthe implant provides an extremely strong interface between the implantand surrounding natural bone. As such, the likelihood that the implantwill loosen is greatly reduced. Further, the overall long-termacceptance of the implant in the bone is increased.

Other advantages of the present invention are discussed in connectionwith the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of one embodiment of a dental implant of thepresent invention.

FIG. 2 is a cross-sectional view of the implant of FIG. 1 embedded in ajawbone of a patient.

FIG. 3 is a side view of another embodiment of a dental implant of thepresent invention.

FIG. 4 is a cross-sectional view of FIG. 3.

FIG. 5 is a side view of yet another embodiment of a dental implant ofthe present invention.

FIG. 6 is a cross-sectional view of FIG. 5.

FIG. 7 is side view of another embodiment of a dental implant of thepresent invention.

FIG. 8 is a top view of the FIG. 7.

FIG. 9 is an alternate top view of FIG. 7.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, an implant 10 is shown according to theinvention. Implant 10 is preferably constructed of a biocompatiblematerial such as titanium and includes two primary components or bodies,a coronal body 14 and a bone fixation body 16.

The coronal body 14 has a short cylindrical configuration that extendsfrom a proximal end surface 20 to a distal end surface 22. Atransgingival section 24 is formed with a smooth outer surface. A dentalinterface 26 extends upwardly and adjacent the transgingival section.This interface (also referred to as an abutment-engaging end) is formedas a male hexagonal connector. The interface can have other embodimentsknown in the art, such as splines, internal and external octagons,stars, and other polygons. A threaded bore 28 extends into the coronalbody and is adapted to receive a fixation screw for connecting thedental implant to a dental component, such as an abutment, prosthesis,healing collar, or the like. Preferably, the coronal body 14 is formedof a biocompatible metal, such as a solid metal piece of titanium ortitanium alloy. The body can be machined to have a size and shape shownin the figures.

The bone fixation body 16 has an elongated cylindrical shape thatextends from a proximal end 30 to a rounded distal end 32. Body 16 isformed from as a porous metal, such as titanium. Preferably, the bodyhas a completely porous structure that extends throughout the entirebody from the proximal to distal ends. Specifically, as shown in FIG. 2,body 16 does not include a metal substrate. The distal end surface 22 ofcoronal body 14 connects or fuses to the proximal end 30 of the bonefixation body 16 at a junction 40.

FIG. 2 shows the implant 10 embedded in a jawbone 34 of a patient.Preferably, the length of the body 16 extends along the region where theimplant contacts surrounding bone 36 once the implant is implanted intothe jawbone. The transgingival section 24 extends along the gum tissueor gingival tissue 38.

As noted, the bone fixation body 16 has a porous structure that extendsfrom the outer surface and throughout the body. By “porous,” it is meantthat the material at and under the surface is permeated withinterconnected interstitial pores that communicate with the surface. Theporous structure can be formed by sintering titanium or titanium alloypowder, metal beads, metal wire mesh, or other suitable materials knownin the art.

One advantage of the present invention is that the porous structure ofbody 16 is adapted for the ingrowth of cancellous and cortical bonespicules. More particularly the size and shape of the porous structureemulates the size and shape of the porous structure of natural bone.Preferably, the average pore diameter of body 16 is about 40 μm to about800 μm with a porosity from about 45% to 65%. Further, theinterconnections between pores can have a diameter larger than 50-60microns. In short, the geometric configuration of the porous structureshould encourage natural bone to migrate and grow into and throughoutthe entire body 16.

Preferably, body 16 is created with a sintering process. One skilled inthe art will appreciate that many variations exist for sintering, andsome of these variations may be used to fabricate the present invention.In the preferred embodiment, the coronal body is prepared usingconventional and known machining techniques. Next, a ceramic mold isprovided. The mold has a first cavity that is sized and shaped to matchthe size and shape of the bone fixation body. In this first cavity, thesintering material can be placed. The mold also has a second cavity thatis adjacent and connected to the first cavity. This second cavity issized and shaped to receive the coronal body. The coronal body ispositioned in the second cavity such that the distal end surface isadjacent and continuous with the first cavity.

The sintering material is then placed into the first cavity. Thismaterial may be a titanium alloy powder, such as Ti-6Al-4V. Some of thispowder will contact the distal end surface of the coronal body. The moldis then heated to perform the sintering process. During this process, asthe material in the first cavity heats and sinters, the bone fixationbody forms and simultaneously bonds or fuses to the distal end surfaceof the coronal body.

The size and shape of the pores and porous structure produced in thefirst cavity depend on many factors, These factors include, for example,the temperature obtained in the furnace, the sintering time, the sizeand shape of sintering material, the composition of the sinteringmaterial, and the type of ceramic mold used. These factors (and others)can be varied to produce a bone fixation body in accordance with thepresent invention. Further, these factors (and others) can be varied toproduce a strong bond between the bone fixation body and coronal body.

Once the sintering process is finished, the distal surface of thecoronal body is directly fused to the bone fixation body. These twobodies are now permanently connected together to form the dentalimplant.

In the aforementioned sintering process, the bone fixation bodysimultaneously forms and attaches to the coronal body. One skilled inthe art though will appreciate that each of these bodies can befabricated independently and subsequently connected together. If thebodies are made separately, then they may be attached or fused togetherusing known welding or brazing techniques, for example.

FIGS. 3 and 4 show another implant 50 according to the invention. Withsome differences, implant 50 is similarly configured to the implant 10.As one difference, the bone fixation body 52 has a gradual andcontinuous taper that extends from the proximal end 54 to the distal end56. Further, the coronal body 60 has two different and distinct regionson the outer surface. A first region 62 has a smooth outer surface. Asecond region 64 has a bone-engaging surface that is contiguous andadjacent to the first region 62 on one side and contiguous and adjacentthe porous bone fixation body 52 on the other side. The second region isnon-porous and can be formed with various techniques known in the art.These techniques include, for example, coating with HA, grit-blasting,etching, micro-texturing, other non-porous surface treatments, orcombinations of these techniques. This surface is provided as anintermediate zone between the porous body and the smooth first region62.

FIGS. 5 and 6 show another implant 70 according to the invention. Withsome differences, implant 70 is similarly configured to the implant 10.As one difference, implant 70 has a bone fixation body 72 with an outersurface that has a plurality of undulation 74, such as hills andvalleys. These undulations are adapted to firmly secure the implant intothe jawbone after the implant is placed therein. Further, the coronalbody 80 has a dental interface 82 formed as an internal connection, suchas an internal hexagon or other internal polygon. Further yet, thedistal end surface 84 of the coronal body has an elongated protrusion 86extending outwardly. This protrusion extends into the bone fixation body72 and is adapted to increase the interface between the coronal body andbone fixation body. This protrusion may have various configurations,such as non-tapering, tapering, cylindrical, square, rectangular,hexagonal, octagonal, polygonal, or other shapes. Preferably, theprotrusion is formed as a cylinder or square.

FIGS. 7 and 8 show another implant 100 according to the invention. Withsome differences, implant 100 is similarly configured to the implant 10.As one difference, implant 100 has a bone fixation body 102 with anuneven outer surface 104. This surface is adapted to aid in boneintegration and anti-rotation between the bone fixation body andsurrounding bone. Further, the coronal body 110 has two different anddistinct regions on the outer surface. A first region 112 has a smoothouter surface; and a second region 114 has a bone-engaging surface.These regions are similar to the regions 62 and 64 described inconnection with FIGS. 3 and 4.

As yet another difference, the coronal body 110 has a shape and sizeadapted to conform to the size and shape of natural teeth. The shape ofthis body is particularly advantageous in single-stage dental implants.The shape and size of the coronal body can thus contour the gingival orgum tissue to a natural shape that surrounds teeth. The size and shape,for example, can be similar to a molar, premolar, or incisor. FIG. 8shows a top view of the coronal body 110 to have a shape of an oval orellipse. As shown in FIG. 7, coronal body can taper upwardly from thedistal end 120 to proximal end 122.

FIG. 9 shows a top view of the coronal body 110 in an alternateembodiment to have a triangular shape.

As another advantage of the present invention, the bone fixation bodycan be adapted to induce bone growth into and entirely through the body.The body, for example, can be doped with biologically active substances.These substances may contain pharmaceutical agents to stimulate bonegrowth all at once or in a timed-release manner. Such biological activesubstances are known in the art.

Although illustrative embodiments have been shown and described, a widerange of modifications, changes, and substitutions is contemplated inthe foregoing disclosure; and some features of the embodiments may beemployed without a corresponding use of other features. Accordingly, itis appropriate that the appended claims be construed broadly and in amanner consistent with the scope of the embodiments disclosed herein.

1. A dental implant, comprising: a coronal body formed of solid metaland connectable to a dental component; and a bone fixation bodyconnected to the coronal body and having a porous metal structure thatcontinuously extends through an entire cross-sectional view of the bonefixation body and includes a center of the body in the cross-sectionalview.
 2. The dental implant of claim 1, wherein the porous metalstructure includes interconnected interstitial metallic pores thatcommunicate through the center from one side of the bone fixation bodyto an opposite side of the bone fixation body.
 3. The dental implant ofclaim 1, wherein the porous metal structure induces bone growth into andentirely through the bone fixation body and the center in thecross-sectional view.
 4. The dental implant of claim 1, wherein thecoronal body is prepared using a machining technique and the bonefixation body is prepared using a sintering technique.
 5. The dentalimplant of claim 1, wherein the bone fixation body has at least oneportion in the cross-sectional view where the porous metal structureextends entirely throughout the bone fixation body including the center.6. The dental implant of claim 1, wherein the bone fixation body isformed of porous titanium that bonds to the coronal body during asintering process.
 7. The dental implant of claim 1, wherein the bonefixation body has an elongated cylindrical shape with externalundulations.
 8. A dental implant, comprising: a coronal body formed ofsolid metal; and an elongated body connected to the coronal body andhaving a metallic porous structure portion that continuously extends, ina cross-sectional view of the body, from a first outer surface of thebody to an oppositely disposed second outer surface of the body, whereinthe metallic porous structure portion completely fills interior andcentral portions of the body in the cross-sectional view.
 9. The dentalimplant of claim 8, wherein the metallic porous structure is formed oftitanium and connects to the coronal body during sintering.
 10. Thedental implant of claim 8 further comprising, a solid metal protrusionthat extends from the coronal body and partially extends into themetallic porous structure of the body.
 11. The dental implant of claim8, wherein the metallic porous structure portion enables bone to growinto and through the interior and central portions of the body.
 12. Thedental implant of claim 8, wherein the metallic porous structure portionis doped with a biological active substance to induce bone to growthrough a center of the body in the cross-sectional view.
 13. The dentalimplant of claim 8, wherein the metallic porous structure portioncomprises material, at and under the first and second outer surfaces,with interconnected interstitial pores that communicate with the firstand second outer surfaces.
 14. A dental implant, comprising: a headformed of solid metal; and a body connected to the head and havinginterconnected metallic pores that continuously extend, in across-sectional view of the body, from a first surface of the bodythrough an internal portion to a second surface of the body, the secondsurface being opposite the first surface, wherein the interconnectedmetallic pores induce bone growth through the internal portion andthrough a center of the body in the cross-sectional view.
 15. The dentalimplant of claim 14, wherein the interconnected metallic pores have ageometric configuration to encourage natural hone to migrate and growfrom the first surface through the center to the second surface.
 16. Thedental implant of claim 14, wherein an external surface of the body hasundulations that include hills and valleys.
 17. The dental implant ofclaim 14, wherein the body has a least one portion in thecross-sectional view that is completely comprised of the interconnectedmetallic pores so bone grows throughout the center and the internalportion.
 18. The dental implant of claim 14, wherein the interconnectedmetallic pores encourage growth of cancellous and cortical bone spiculesthrough the center.
 19. The dental implant of claim 14, wherein theinterconnected metallic pores include a substance to stimulate bonegrowth in a time-released manner.
 20. The dental implant of claim 14,wherein the body has an uneven outer surface with hills and valleys toaid in anti-rotation between the body and surrounding bone.
 21. Amethod, comprising: using a machining technique to form a coronal bodymade of solid metal; using a sintering technique to form a bone fixationbody having a porous metal structure that continuously extends throughan entire cross-sectional view of the bone fixation body and includes acenter of the body in the cross-sectional view; and connecting thecoronal body formed of solid metal to the bone fixation body formed ofporous metal.
 22. The method of claim 21, wherein the bone fixation bodybonds to the coronal body during the sintering technique.